1. Field of the Invention
The present invention relates to a keyboard apparatus having a frame integrally formed by resin and pivotably supporting a plurality of keys, and more particularly, to a keyboard apparatus having hammers supported on a frame so as to each pivot in conjunction with a corresponding key and impart inertia to the key.
2. Description of the Related Art
Conventionally, keyboard apparatuses have been known in which a frame integrally formed by resin and pivotably supporting a plurality of keys is adapted to be supported on a musical instrument main body. Among these, some keyboard apparatus includes hammers supported on the frame and each adapted to pivot in conjunction with a corresponding key and impart inertia to a pivotal motion of the key (Japanese Patent Publication No. 3819136 and Japanese Laid-open Patent Publication No. 7-181959).
In the keyboard apparatuses disclosed in Japanese Patent Publication No. 3819136 and Japanese Laid-open Patent Publication No. 7-181959, each hammer is adapted to be driven by the corresponding key so as to pivot about a hammer support, and a stopper is provided at either a lower rear part or a lower front part of the frame. In a non-key-depression state, the hammers are in contact with an upper surface of the stopper at their one end portions (contact parts) where the hammer's mass is concentrated, whereby initial pivot positions of the hammers are restricted and key-depression initial positions of respective keys are indirectly restricted.
Therefore, height positions of key-depression surfaces (i.e., upper surfaces) of the keys in the non-key-depression state are determined by contact states between the stopper and the contact parts of the hammers.
In the keyboard apparatus disclosed in Japanese Patent Publication No. 3819136, since the distance between the contact part of each hammer and the corresponding hammer support is long, the contact part is caused to come into contact with the stopper at high speed when the hammer restores to its initial pivot position. Thus, the stopper is liable to be deformed due to repetitive restoration motions of the hammers, resulting in a variation between the height positions of the key-depression surfaces of the keys. If the thickness of the stopper is thickened to suppress the stopper deformation, the stopper thickness tends to greatly vary between different portions of the stopper, causing a variation between the height positions of the key-depression surfaces of the keys.
If the distance between the hammer support and the contact part of each hammer is long, warpage and deformation of the hammer in a region between the hammer support and the contact part affect the key-depression initial position of the corresponding key, resulting in a variation between the height positions of the key-depression surfaces of the respective keys.